Solve this fast

Example 10.2. A flat furnace wall is constructed of a 4.5-in. (114-mm) layer of Sil-o-cel brick, with a thermal conductivity of 0.08 Btu/ft-h-F (0.138 W/m-C) backed by a 9-in. (229-mm) layer of common brick, of conductivity 0.8 Btu/ft-h-F (1.38 W/m-C). The temperature of the inner face of the wall is 1400F (760C), and that of the outer face is 170F (76.6C). (a) What is the heat loss through the wall? (6) What is the temperature of the interface between the refractory brick and the common brick? (c) Supposing that the contact between the two brick layers is poor and that a "contact resistance of 0.509F--A2/Btu (0.088C-m-/W) is present, what would be the heat loss